Cinematographic apparatus



y 1941- L. E. WHITTAKER 2,241,689

GINEMATOGRAPHIC APPARATUS Filed May 31, 1939 2 Sheets-Sheet l tain thepull of the film Patented May 13, 1941 UNITED STATES PATENT OFFICEcmmmoziizmm'rus v Llored n.

. signer to tion, Los Angeles, Calif Application May 31, 1939, SerialNo. 276,567

.1 Claim- ((1242-55) In various kinds of cinematographic apparatus it iscustomary to drive him take-up reels through a friction clutch whichtends to drive the reel somewhat faster than the film is delivered fromthe apparatus, the clutch slipping to accommodate the differences inspeed. As the diameter of the roll of film on the take-up reelincreases, the pulling force exerted on the film by the friction clutchgradually decreases because of the gradually increasing torque radius.The drag of the clutch is ordinarily adjusted to exert the necessarypull on the film at the maximum diameter of the roll. Consequently thepull on the film is much greater than necessary until the roll of filmbuilds up to maximum diameter. While this is satisfactory for ordinaryfilm wound in small rolls, there is a tendency to damage the film in thecase of certain kinds of special film and/or in case of extra largerolls of film.

The object of the present invention is to mainby the take-up reel moreuniform as the roll increases in diameter and more particularly to avoidexcess pull on the film while the diameter of the roll is still small.

According to the present invention the apparatus comprises, incombination with means for exerting a yielding drag on the take-up reelin the direction tending to wind the film upon the reel, means forautomatically and progressively increasing the drag as reel, therebyprogressively to increase the driving force applied to the reel as thediameter of the roll increases. While the increase in the drag should bedirectly in proportion to the increase in diameter of the roll, theproportion need not be in straight-line relationship. The apparatus maycomprise a driven rotor, such as a shaft, for rotating the reel, adriving rotor, such as a tubular shaft surrounding the driven shaft, andan ordinary dry-plate clutch interconnecting the two rotors. In itspreferred form the apparatus comprises a tubular screw surrounding thereel shaft, with a compression spring between the clutch and screw forpressing the friction surfaces together, and means driven by the shaftfor advancing the screw to increase the tension of the spring inproportion to the increase in diameter of the roll of film on thetake-up reel.

For the purpose of illustration a typical embodiment of the invention isshown in the accompanying drawings in which Fig. 1 is an axial sectionshowing parts in top plan;

Fig. 2 is a section on line 2--2 of Fig. 1;

the film winds on the Whittaker, North Hollywood, 03111., aslor MotionPicture Corporaa co p ration of Maine Fig. 3 is away; and

Fig. 4 is a section on line 4-4 of Fig. 1.

For the purpose of illustration the apparatus is shown in connectionwith a film magazine I mounted on the housing 3 by interengaging parts 2and 4. The take-up reel is shown at 5 and the roll of film at 6. Thetake-up reel is driven by a shaft 1 having portions 8, 9, l0 and H ofdifferent diameters with shoulders l2, l3, l4 and I5 between theportions of different diameters. Surrounding the shaft 1 is a tubularshaft I6 which is spaced from the shaft 1 by means of bearing rings l1and I8 which are fast to one shaft and freely. rotatable on the othershaft. At one end the shaft i6 is provided with a clutch housing lit towhich is attached, by means of screws 20, a worm gear 2| which is drivenby a suitable source of power though the worm 22, shaft 23, worm gear24, worm 25 and shaft 26 leading to the source of power. This chain ofdriving means is enclosed in a sub-housing comprising two caps 2'! and28. The tubular shaft i6 is journaied in the housing 3 by means of ballbearings 29 and 30.

a gside elevation with parts broken Disposed within the housing [9 areclutchrings 34 and 36 which are pressed together by a coil spring 3iextending between the collars 32 and 33, recurrent plates 34 beingprovided with external lugs extending into a keyway 35 so that theseplates must rotate with the housing and one or more of the intermediateplates 36 being provided with internal lugs extending into a keyway 31so that these plates are non-rotatabiy associated with the shaft 1.Between the plates of the two sets are friction rings 38.

The means for varying the tension of the compression spring 3| comprisesa tubular screw 40 surrounding the shaft 1 and threading through abushing 41 mounted in a portion 42 of the housing 3, the screw beingspaced from the portion 9 of the shaft I by means of a sleeve 43.Intermediate the collar 33 and the screw 40 is a thrust bearing 44.integrally connected with the screw 40 is a gear wheel 45 to which isattached, by means of screws 46 (Fig. 2), a ratchet wheel 41.Surrounding the portion III of shaft 1 is a sleeve 48 carrying twointegral arms 49 and 50. Pivotally mounted on the outer end of the arm49 is a pawl 5| which is normally held in engagement with the teeth onthe periphery of the ratchet wheel 41 by means of a spring 52, a handle53 projecting from the pawl outwardly through an opening in the casing54 for disengaging the pawl from the ratchet wheel when the apparatu isto be reset. Rotatably mounted on the outer end of the arm 50 is aroller 55 engageable with a cam 68 on the shaft II, this shaft beingdriven by a worm gear 58 meshing with a worm as on the portion ll of theshaft 1. A spring 60 yieldingly holds the roller II in contact with thecam 58.

For resetting the screw 40 when a new reel is applied to the apparatus apinion H is mounted on shaft 62 which extends outwardly through thecasing 54 to a hand wheel Iii. In the normal position of the pinion 6|it is disengaged from the apparatus as shown-in Fig. 3, but when it isdesired to operate the screw 40 by hand the shaft 62 is pushed inwardlyuntil the pinion 6| meshes with the gear 46, whereupon the screw may beturned by hand in either direction. If the screw is to be retracted, asin resetting the apparatus for a new reel, the pawl BI is lifted out ofengagement with the ratchet wheel 41' by means of the handle 53 whilethe screw is being retracted.

In operation the reel 5 is driven through the following train ofmechanism: shaft 24 (Fig. 4), worm 25, gear 24, shaft 23, worm 22, gear-2|, tubular rotor l6 (Fig. 1), clutch 3446 and shaft 1. As shaft 1rotates it causes the pawl 5| to oscillate back and forth through thefollowing train of mechanism: shaft 1, worm 5!, gear 58 (Fig. 2), shaft51, eccentric cam 56, roller 55 and arms 50-49; Thus the pawl oscillatesback and forth once for each revolution of the shaft 51.

The number of revolutions of the shaft 1 per oscillation of pawl ll maybe in any desired ratio depending upon-the gear ratio of worm II and.

gear 44. At each oscillation of the pawl ii the screw is advanced a partturn through the ratchet wheel 41 fast to the screw, thereby to increasethe tension of the compression spring I I.

It should be understood'that the present disclosure is for the purposeof illustration only and that this invention includes all modificationsand equivalents which fall within the scope of the appended claim.

I claim:

cinematographic apparatus for driving a film take-up reel, comprising ashaft for rotating the reel, a tubular rotor surrounding a portion ofthe shaft, a friction clutch surrounding the shaft at the end of thetubular rotor with friction surfaces non-rotatably associated with theshaft and rotor respectively, a tubular screw surrounding said shaft onthe side of the clutch opposite the rotor, a compression spring betweenthe clutch and screw for pressing said friction surfaces together, andmeans driven by said shaft for turning the screw to increase the tensionof the spring in proportion to the increase in diameter of the roll offilm on the take-up reel,

thereby progressively to increase th driving force applied to the reelas the diameter of the roll of film increases.

LLOYED E. WHIT'IAKER.

